Illarion.org

This doesn't happen often, and it fixes itself after a while, but it does affect more than one computer, because it has happened on two diffrent machines, but what happens, is the red square will dissappear under the target, it highlights it, then dissappears after a second, meaning I have to re-target the enemy it and I'll get a hit on it, and it dissappears again.
It may not sound like a huge problem, but it makes it a lot harder to fight somthing, and it has cost the life of my character a few times.

Sometimes you need to push yourself or the enemy to solve it. It usually happens sporadically and is a bug, I would think. I can't find any reason for this to happen, though, because it happens to different NPCs and people sporadically.

it happens to me also i always wondered what caused it

That bug got me killed once, I think. I can't remember though.

i have the same problems. it is really dangerous while ya fighting strong enemys

I believe this is linked to the bug that produces false images of chars along their way, as it usually happens within the range of respawn or teleport points/ doors. The easiest way to avoid it is to walk away from such points until you can target your enemy properly.

No I've tried that but it keeps happening with Skeletons as far away as the monestary.

I believe this is usually solved by dragging yourself (preferably diagonally backwards, to avoid strong enemy attack as well).